# 15 18 24 triangle

### Obtuse scalene triangle.

Sides: a = 15   b = 18   c = 24

Area: T = 134.8311144399
Perimeter: p = 57
Semiperimeter: s = 28.5

Angle ∠ A = α = 38.62548328731° = 38°37'29″ = 0.67441305067 rad
Angle ∠ B = β = 48.50991831443° = 48°30'33″ = 0.84766449633 rad
Angle ∠ C = γ = 92.86659839826° = 92°51'58″ = 1.62108171836 rad

Height: ha = 17.97774859199
Height: hb = 14.98112382666
Height: hc = 11.23659286999

Median: ma = 19.8433134833
Median: mb = 17.87545629317
Median: mc = 11.42436596588

Inradius: r = 4.73109173473
Circumradius: R = 12.01550281837

Vertex coordinates: A[24; 0] B[0; 0] C[9.93875; 11.23659286999]
Centroid: CG[11.31325; 3.74553095666]
Coordinates of the circumscribed circle: U[12; -0.60107514092]
Coordinates of the inscribed circle: I[10.5; 4.73109173473]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 141.3755167127° = 141°22'31″ = 0.67441305067 rad
∠ B' = β' = 131.4910816856° = 131°29'27″ = 0.84766449633 rad
∠ C' = γ' = 87.13440160174° = 87°8'2″ = 1.62108171836 rad

# How did we calculate this triangle?

Now we know the lengths of all three sides of the triangle and the triangle is uniquely determined. Next we calculate another its characteristics - same procedure as calculation of the triangle from the known three sides SSS. ### 1. The triangle circumference is the sum of the lengths of its three sides ### 2. Semiperimeter of the triangle ### 3. The triangle area using Heron's formula ### 4. Calculate the heights of the triangle from its area. ### 5. Calculation of the inner angles of the triangle using a Law of Cosines    